In general, a cold cathode X-ray source attracts electron beams from a carbon nanotube electron emitter by applying a voltage to a gate electrode and then focuses the electron beams to high density through a focusing electrode and induces them to an anode electrode. In this case, if a high voltage is applied between a cathode electrode and an anode electrode, electrons are accelerated toward the anode electrode and collide with the anode electrode, and, thus, an X-ray is generated from the anode electrode.
According to the conventional cold cathode electron emission technology, a carbon nanotube has mainly been used as an electron emitter and an electron emitter has been manufactured by mixing the carbon nanotube and a conductive organic material to a paste. However, while the carbon nanotube paste electron emitter is manufactured, the carbon nanotube which serves as a field emitter can be contaminated by unwanted organic material and it is very difficult to achieve vertical orientation. Further, while the carbon nanotube paste electron emitter is operated, the field emission efficiency is greatly decreased due to the ionization of gas molecules caused by the organic material remaining in the paste and the lifetime of the carbon nanotube that emits electrons is reduced.
Further, in a conventional cold cathode X-ray source, a metal mesh or metal hole has mainly been used as a gate electrode. In this case, the transmission efficiency of electrons passing through the gate electrode is decreased.
In this regard, Korean Patent No. 10-1239395 (entitled “Field emission source, device adopting the source, and fabrication method of the device”) discloses a field emission source having a stable electron emission material support structure, a field emission device adopting the field emission source, and a fabrication method of the field emission device.